Comparison of Growth and Survival of Brown Mussel (Mytilopsis adamsi) Cultured in Estuarine and Marine Waters

Abstract

The brown mussel (Mytilopsis adamsi) is a small bivalve mollusk that typically reaches a maximum length of 1.5 cm. It is a filter feeder, consuming zooplankton, phytoplankton, and suspended organic matter. Originally distributed throughout the Indo-Pacific region, this species is now found in several countries, including Malaysia, Taiwan, and Australia. In Indonesia, brown mussels have recently begun to be cultivated, primarily as a natural feed source for economically valuable crustaceans such as crabs and lobsters. This study aimed to determine the differences in the growth and survival of brown mussels (M. adamsi) in the estuary and marine environments. The importance of this study was in determining the optimal location for cultivating brown mussels (M. adamsi). The experiment consisted of 2 treatments (estuarine and marine), with 10 replicates per treatment, resulting in a total of twenty experimental units, using 50 brown mussels (Mytilopsis adamsi) per replication. Data that followed a normal distribution were analyzed using an independent samples t-test at a significance level of p < 0.05. The data did not meet the assumption of normality, the non-parametric Mann–Whitney U test was used as an alternative statistical method. The culture experiment was conducted for 90 days in two locations: an estuarine zone in Bagek Kembar Village and a marine zone in Cendi Manik Village, West Lombok Regency, West Nusa Tenggara, Indonesia. The results showed that absolute, relative, and specific length, as well as the survival rate of brown mussels, were significantly higher (p < 0.05) in the estuarine zone compared to the marine zone. The estuary zone's absolute, relative, and length-specific growth were 19.70 mm, 608%, and 2.35%, respectively, and the survival rate was 70%. Meanwhile, the absolute, relative, and length-specific growth in the marine zone were 13.12 mm, 471%, and 1.95%, respectively, and the survival rate was 57%. The average length of mussels in the estuary and marine environment reached 22 mm and 15 mm, respectively. The final weight of the mussels in the estuary was 1.10 g, while in the sea was 0.48 g. The weight of the mussel meat cultured in the estuary zone was around 0.71 grams per mussel, which was higher than mussel meat cultured in the seawater, which was around 0.19 grams per mussel. The total organic matter in the estuary and the marine zone was 70-110 mg/L and 35-65 mg/L, respectively. This study demonstrates that the estuarine environment provides significantly more favorable conditions for the growth and survival of brown mussels (Mytilopsis adamsi) compared to the marine environment. Estuarine waters, formed at the confluence of seawater and freshwater, create nutrient-rich ecosystems with abundant natural food sources that promote faster mussel growth. In contrast, marine waters are characterized by higher salinity and limited nutrient availability, which may constrain the growth performance of M. adamsi.